1. Field of the Invention
Aspects of the present invention relate to a method and apparatus for controlling the transfer of paper, and more particularly, to a method and apparatus for controlling the transfer of paper that is fed into a color image forming apparatus.
2. Description of the Related Art
As the printing speed of printers has increased, there are times when the printers cannot efficiently supply a sufficient number of sheets of paper when the printer only has a primary paper-feeding unit and a large number of pages needs to be printed. In those situations, a user has to load paper frequently in order to print the large number of pages. To solve such inconveniences, an auxiliary paper-feeding unit is used that is detachable from the printers, contains a large number of sheets of paper, and can be used even in different printers. However, in order to use such an auxiliary paper-feeding unit on different printers, the auxiliary paper-feeding unit must be customized each time to correspond to the structure and performance of each of the printers, so that a sheet of paper can be reliably transferred to that particular printer and be printed.
A procedure for transferring a sheet of paper loaded in an auxiliary paper-feeding unit will now be described. When a printer starts printing, the sheet loaded in the auxiliary-paper feeding unit is transferred to the printer by action of a driving unit of the auxiliary-paper feeding unit. When the sheet is transferred to the printer, the printer aligns the leading end of the sheet to minimize skewing of the printed image. More specifically, the printer stops the driving force of a registration unit that moves the leading end of the sheet, and aligns the leading end of the sheet while an image is formed on a photosensitive drum of the printer. While the printer is aligning the leading end of the sheet, the driving unit of the auxiliary paper-feeding unit continuously transfers the sheet, and thus the sheet can be crumpled between the registration unit and the driving unit.
Especially, in the case of a color printer, since the photosensitive drum of a color printer needs an image to be formed on the photosensitive drum more than three times, it takes a substantial amount of time to form the image on the photosensitive drum, and consequently, the time consumed to align the leading end of the paper increases, thereby causing more serious bending or crumpling of the sheet than occurs in a black-and-white printer.